By that I mean that if one civ has Radio and the other doesn't, then the more advanced civ should gain some combat benefit.

Also, if one Civ has radio and 'Polymorphic/Digital Encryption' or something similar, and the other Civ just has Radio, then there should be an advantage because you can listen in to you're opponent and they can't.
This could also be represented by tge encryption advance givintg a support unit 'Electronic Warfare Team' that listen and scramble vulnerable enemy communications, so giving an advantage to any freindly units in neighbouring squares in combat with units that aren't protected by similar enemy units (and have radios too). This advantage should be larger, +50% ish, as you've got a special unit doing the work.

These are not cumulative, if you're opponent doesn't have radio, then it makes no difference if your's are encrypted.

Not sure about this one, but how about getting an advantage if you have 'Writing', or 'Literacy' or 'Beurocracy'. Hmmm, still don't know about that one.

Alternatively this could be a set of 'Feats of Wonder' as in CTP II, although this is the easiest fix, and least satisfactory to me..